Identification of Symptoms of Zucchini Gray Mold and Its Control Methods
Zucchini is a vegetable rich in vitamin C and glucose, and a member of the gourd family. When stir-fried as a vegetable, it has a relatively crisp texture and a very mild flavor. Zucchini is grown in many places, and improper management or environmental factors can lead to gray mold. Let us take a look below at the symptoms of zucchini gray mold and an introduction to its control methods.
I. Symptoms of zucchini gray mold
It mainly damages flowers, young fruit, leaves, stems or larger fruit. The gray mold fungus first invades from spent female flowers. In the early stage of infection, the petals appear water-soaked, and the flower surface is densely covered with a white frost. Later they become soft and rot and develop a grayish-brown mold layer, causing the petals to rot, wilt and fall off. The disease spreads from diseased flowers to the stem end of the young fruit, causing the stem end of the young fruit to lose its green color and gradually become water-soaked wet rot and shrink, producing a gray mold layer. Fruit mostly begins to develop the disease from the tip; the affected part first becomes soft and rots until the entire fruit becomes soft-rotted, and a gray mold layer forms on the fruit surface. If diseased tissue falls on leaves or stems and vines, it can also cause disease in the stems and leaves. Leaf spots are initially water-soaked, then turn light grayish-brown, with relatively distinct edges, sometimes with gray mold-like material in the middle, and sometimes with indistinct brown concentric rings, forming irregular large spots. When stems and vines are affected, grayish-white lesions appear, bearing grayish-brown mold-like material; after encircling the stem, they fester, causing the stem and vine to break and the forward vine to die. The gray color of the diseased parts of this disease distinguishes it from zucchini brown rot. The symptoms of the two diseases are similar, but the pathogens are different, so the control methods and the fungicides used are different, and care must be taken to distinguish them in production.
II. Control methods for zucchini gray mold
1. Use high-ridge mulched grafted cultivation. Using black-seed pumpkin as the rootstock and zucchini seedlings as the scion, grafting can increase zucchini's ability to resist gray mold. During agricultural operations, try to avoid causing wounds and reduce the human spread of the disease.
2. Hanging-vine cultivation. Begin hanging the vines when zucchini has grown to 8 leaves.
3. Apply drip irrigation and water at the proper time. In the morning, try to maintain a relatively high temperature and allow the dew in the greenhouse to vaporize; in the afternoon, increase ventilation to reduce humidity in the greenhouse; at night, appropriately raise the greenhouse temperature to reduce or avoid condensation on the leaf surface.
4. Chemical flower dipping. After zucchini blooms, when dipping flowers every morning, add 0.1% procymidone or carbendazim and other fungicides to 2,4—D to effectively control zucchini gray mold.
5. Clean the greenhouse film and promptly remove diseased flowers, diseased leaves, diseased fruit and other diseased tissue, and promptly take them out of the greenhouse for destruction. In the later stage of production, promptly clean up old leaves to increase ventilation and light penetration, so that the plants grow robustly and their disease resistance increases.
6. Chemical control. In the early stage of disease in the greenhouse, spray 50% procymidone wettable powder at 2000 times dilution, or 50% iprodione wettable powder at 1000-1500 times dilution. For greenhouse cultivation, minimize spraying to avoid increasing humidity in the greenhouse. You can use 10% procymidone smoke agent at 3-3.75 kg/ha, or 45% chlorothalonil smoke agent at 3.75 kg/ha, and fumigate for 3-4 hours.